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Ask HN: How do you keep a client from stealing your excel spreadsheet?

2 points by graham1776 ↗ HN
We have developed a financial model in excel worth in the neighborhood of $75-100k and many people in our industry have similar financial models.

How would you keep it from being stolen if you wanted a client/employee to use it without taking it with them or using a copy on their own PC? Is there a way to allow use of an excel model without ownership?

7 comments

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pettycash
implement a DRM mechanism. One way is to build an authentication server, log against a license, and rotate licenses as needed if you find curious activity. This is not a new problem and has been done previously. You may need to get creative with the code. I'm assuming that your model is quite visible for someone to reverse engineer by looking at VB project in Excel. You need to find a way to hide it as well.
graham1776
Not going to lie, sounds like brain damage, especially for super non-technical real estate folks (I am one).

What do you think about a Citrix/Virtual Machine where the client could use the excel sheet over internet, play with it, without any connection to the outside world (ie email, dropbox, internet). Owner of the document would have full ability to download and edit, but client would only be able to edit and save within the virtual machine... Overcomplicating much?

pettycash
sure - I understand. I can't comment on Citrix/VM setup. Once they have access to the document, they will be able to screenshot it. etc.

Sounds like you need to keep it simple. I did a google search for "excel document drm solutions". You'll need to investigate all solutions for yourself, but looks like there are plenty off the shelf solutions.

beauzero
If it's worth that why hasn't it been converted to something easier to control...or is that what was paid to develop it (not actual value)?
graham1776
Functionally, that is what would have been paid by someone else to develop it. It was built in house.

Honestly, us real estate folks are scared of what they don't know. Excel is familiar so converting it to our own software or web platform is not going to happen.

I just figured there would be a solution or service where users could use an excel document in a neutral place where the owner of the document could let people use the functionality of the document without stealing the source. Its like every excel document, once sent to someone else, is functionally open-source.

spreadsheetguru
you implement it on the serverside as an API or webapp that you sell as a service. There are many ways of doing this, for example resolver one, or ethercalc. In the olden days would have probably written a webapp that interfaced with excel directly using the COM APIs, but that went aggainst MSFT's EULA.
eddyparkinson
use www.cellmaster.com.au (disclosure I am the founder) At the moment it is free for low volume usage.

These also look like they would do what you want, maybe spreadsheetconverter depends on your needs:

BaseCase.com

stoic.com

www.spreadsheetconverter.com

www.smartsheet.com

http://www.forguncy.com/ (Japanese)

www.spreadsheetweb.com

Please tell me more. Details of my email on www.cellmaster.com.au.

P.S. I also like ethercalc as spreadsheetguru suggested - but think many of above would be less work.